Above left, Sen. Jim Jeffords stands with Sen. Patrick Leahy at a 2000 press conference. Above right, Jeffords is led by a police guard into the Radisson Hotel in Burlington on May 24, 2001, as protesters jeer and supporters cheer his decision to leave the Republican Party.

MONTPELIER — For most of his career, Jim Jeffords was one of a now all-but-vanished breed: a moderate-to-liberal Northeast Republican who championed the environment, education and the rights of disabled Americans.

Along with the likes of Sens. Olympia Snowe of Maine, Lincoln Chafee of Rhode Island and Arlen Specter of Pennsylvania, he found himself increasingly out of step with a GOP that was turning sharply to the right.

Jeffords, who died Monday at the age of 80, was the only Republican in the U.S. House to vote against the tax cuts sought by President Ronald Reagan in 1981. Later, as a senator, he voted against President George H.W. Bush’s nomination of Clarence Thomas to the U.S. Supreme Court and, then as an independent, against the Iraq war in 2002.

“I won’t forget I came from Vermont, and Vermont won’t forget I’m in Washington,” he said in a campaign speech early in his career. Eventually, the nation knew the quiet Vermonter was there, too.

“Mr. Jeffords Blows Up Washington,” a Newsweek cover headline proclaimed after Jeffords left the GOP in 2001 and became an independent. The decision shifted control of a tightly divided Senate from the Republicans to the Democrats and left Republicans sputtering.

GOP Leader Trent Lott of Mississippi dubbed Jeffords’ action a “coup of one,” and described it as “the impetuous decision of one man to undermine our democracy.”

The departure broke up the Singing Senators, a quartet that had included Jeffords, Lott, John Ashcroft and Larry Craig.

Jeffords’ shift was a major punctuation mark in a decades-long story that began with the Republicans’ adoption of the famed “Southern strategy” in the 1968 elections and continued with the rise of the modern conservative movement, said Linda Fowler, a professor of political science at Dartmouth College.

“It’s part and parcel of the southernization of the Republican Party,” part of a “major realignment in the U.S. party system going on for about 25 years now,” Fowler said.

Chafee, a former Republican U.S. senator from Rhode Island who is now that state’s Democratic governor, agreed.

“It’s swung south. As the South turned Republican, the agenda just got more and more right wing,” the governor said in an interview.

He called Jeffords part of a generation of well-educated people — Jeffords went to Yale University and Harvard Law School — often with military service in their backgrounds, who went into politics as a public service. “They were just into public service in the fullest extent of the words,” he said.

“I just don’t think the Jim Jeffordses of the new generation would choose to go into the Republican Party,” Chafee added.

Jeffords died at a home for retired military officers — he had been a Navy captain — in Washington, his family and former aides said. Former aide Diane Derby said he had been in declining health.

In his first year in Congress, 1975, Jeffords helped pass the Individuals with Disabilities Education Act, and he remained a champion of disabled Americans throughout his career. He called President George W. Bush’s opposition to an update of that legislation the last straw that led to his leaving the party.

He was a staunch defender of Vermont dairy farmers and led efforts to update federal dairy price supports. He was an early supporter of gay rights, particularly in the workplace.

He also was a strong environmentalist. The last major legislation he offered before leaving the Senate in 2006 was to combat climate change; he had been a key backer of 1990 legislation to toughen the Clean Air Act.

Throughout his career, he angered Republican leaders.

“He was always one of the ones I had to worry about” in the House during the Reagan years, said Lott, R-Miss., a House GOP leader in the 1980s and later Senate majority leader. “He was one of a half-dozen Republicans I had to always watch and make sure I had enough Democrats to make up for the losses if I lost them. Then (Jeffords) moved over to the Senate, same damned thing.”

But he never angered them as when he left the party in 2001.

“He was under enormous pressure not to make the change,” said former Sen. Tom Daschle, D-S.D., who ascended from minority to majority leader after Jeffords made his switch. Daschle said Bush, Vice President Dick Cheney, Senate GOP leaders and senators, and political supporters in Vermont “all brought pressure to bear, and they did it collectively and in a very concerted way.”

But the taekwondo black belt known for his independence bucked them all.

“During his more than 30 years in Washington, Jim never lost the fiercely independent spirit that made Vermonters, and people across America, trust and respect him,” President Barack Obama said Monday.

A funeral is scheduled for 11 a.m. Friday at Grace Congregational Church in Jeffords’ hometown of Rutland. There will be no calling hours, and his burial will be private.